The Truman Doctrine, announced in 1947, had the primary objective of containment of the USSR. This meant that the United States wanted to prevent the further spread of communism, as the USSR was seen as a threat to democracy and capitalist systems.

Option 1: Containment of the USSR - This is the correct answer. The Truman Doctrine was specifically designed to contain the Soviet Union`s influence and halt the spread of communism.

Option 2: Increasing agricultural production in the USA - This option is not directly related to the Truman Doctrine. The Truman Doctrine focused on international relations and containment policies, not agricultural production.

Option 3: Offering friendship to Europe - While the Truman Doctrine aimed to support European countries, it was primarily motivated by the containment of the USSR rather than offering friendship.

Option 4: Strengthening the UNO - Although the Truman Doctrine aimed to support democratic nations and contribute to the stability of global politics, its primary objective was containment, not strengthening the United Nations.

In summary, the Truman Doctrine`s main goal was to contain the USSR and halt the further spread of communism.